Apa bedane antarane CommonJS lan ES Modules ing Node?

Question

Accepted Answer

Node ndhukung **rong sistem modul**: **CommonJS (CJS)** — sing asli, nganggo `require`/`module.exports` — lan **ES Modules (ESM)** — standar, nganggo `import`/`export`. Beda ing sintaks, tingkah laku pemuatan, lan interoperabilitas.

## CommonJS — sing asli Node

```js
// math.js
function add(a, b) { return a + b; }
module.exports = { add };

// app.js
const { add } = require("./math"); // synchronous, runtime
```

## ES Modules — standar

```js
// math.mjs (or .js with "type": "module")
export function add(a, b) { return a + b; }
export default something;

// app.mjs
import { add } from "./math.mjs"; // static, hoisted
```

## Bedane utama

```text
                 CommonJS              ES Modules
Syntax           require/module.exports import/export
Loading          synchronous, runtime  static, hoisted
Top-level await  no                    yes
Tree-shaking     hard                  yes (statically analyzable)
File extension   .cjs / .js (default)  .mjs / .js with "type":"module"
__dirname/__filename available         not available (use import.meta.url)
```

## Ngaktifkan ESM

```json
// package.json
{ "type": "module" }  // now .js files are treated as ESM
```

Utawa nganggo ekstensyon `.mjs` kanthi jelas. Tanpa iki, Node ngatur `.js` menyang CommonJS sacara default.

## Masalah interoperabilitas

```js
// ESM can import CommonJS:
import pkg from "some-cjs-lib"; // works (default import)

// CommonJS CANNOT require() a pure-ESM package (it's async):
const esm = require("esm-only-pkg"); // ❌ ERR_REQUIRE_ESM
// must use dynamic import: const esm = await import("esm-only-pkg");
```

Pinge telak: CJS ora bisa `require()` paket ESM-only — masalah migrasi sing umum. Uga diperhatian manawa ESM ora duwe `__dirname` (nganggo `import.meta.url` sabalihe).

## Mengapa penting

Ngerti rong sistem penting banget kanggo karya Node nyata: ESM yaiku masa depan (standar, tree-shakeable, top-level await, selaras karo browser) lan pilihan sing tepat kanggo proyek anyar, nanging sampeyan banyak ekosistem npm lan kode sing ana yaiku CommonJS.

Mahami bedane sintaks, carane ngaktifkan ESM (`"type": "module"`), lan watesan interoperabilitas (khususé CJS-ora-bisa-require-ESM) nyegah kebingungan lan kesalahan sing kerep tuwuh nalika ngampur-ampur.